Warehousing system using a stacker crane with an improved brake mechanism

ABSTRACT

A self-propelled stacker crane has a tall hoist column captured between a floor mounted horizontal guide rail and a ceiling located horizontal guide tube. A crane carriage is driven along the floor guide rail by a horizontal motor and brake in order to position the crane adjacent horizontally spaced and vertically stacked bins. To eliminate vertical sway and misalignment of the hoist column when the floor driven carriage is braked, a caliper brake mounted at the top of the hoist column is actuated to clamp the ceiling guide tube. The caliper brake is hydraulically actuated under control of a compression spring which is released by deenergization of a solenoid. After a short time delay, the caliper brake may be released by energizing the solenoid in order to correct for any vertical offset in the hoist column.

United States Patent 1 91 Moeller 1 Feb. 12, 1974 WAREHOUSINGSYSTEM USING A STACKER CRANE WITH AN IMPROVED BRAKE MECHANISM [75] Inventor: Ronald P. Moeller, Mendota, Ill.

[73] Assignee: Conco Inc., Mendota, Ill.

[22] Filed: June 7, 1971 [21] App1.No.: 150,291

[52] US. Cl. 214/16.4 A, 188/43, 188/171,

- I 187/9 [51] Int. Cl B65g'l/06 [58] Field of Search 214/164 A, 16.1. EB; 188/67, 188/42, 43, 171

[56] References Cited I 9 UNITED STATES PATENTS 1,762,507 6/1930 Custer 188/171 1,764,797 6/1930 Kersting.... 188/143 1,767,014 6/1930 Rosenberg.... 188/171 1,776,765 9/1930 Ferris 188/42 X 2,647,647 8/1953 Alimanestiano 214/l6.l R 2,726,774 12/1955 Newsom et a1. 2l4/16.1 EB 3,219,207 11/1965 Chasar 2l4/l6.4 A 3,485,389 12/1969 Armington et a1 214/l6.4 A

FOREIGN PATENTS OR APPLICATIONS 1,547,586 10/1968 France 214/16.4 A

' A self-propelled stacker crane has a tall hoist column 7/1960 Great Britain 214/l6.1 EB 8/1891 Great Britain 188/43 Primary ExaminerGerald M. Forlenza Assistant ExaminerR. B. Johnson Attorney, Agent, or Firm-Hofgren, Wegner, Allen, Stellman & McCord ABSTRACT captured between a floor mounted horizontal guide rail and a ceiling located horizontal guide tube. A crane carriage is driven along the floor guide rail by a horizontal motor and brake in order to position the crane adjacent horizontally spaced and vertically stacked bins. To eliminate vertical sway and misalignment of the hoist column when the floor driven carriage is braked, a caliper brake mounted at the top of 8 Claims, 5 Drawing Figures WAREHOUSING SYSTEM USING A STACKER CRANE WITH AN IMPROVED BRAKE MECHANISM This invention relates to a warehousing system using a stacker crane, and more particularly to an improved brake mechanism especially useful for preventing sway and misalignment in the tall vertical mast of a stacker crane.

In stacker cranes, the undriven end of a tall, elongated column mast for vertical hoist will sway to an undesirable degree when the driven end of the stacker crane is braked to a halt. For example, in stacker cranes having a mast height of 50 or 60 feet, a sway or swing of one inch or more is typical despite the rigidity of a well constructed column frame for the vertical hoist. The load fork mechanism cannot be safely operated until a sway of this degree has damped, necessitating a long time delay in the operation of a high speed warehousing system. I r i To prevent sway in tall stacker cranes, it has been conventional to use a torque tube extending the entire height of the vertical mast. The upper end of the torque tube is connected to a gear which coacts with a toothed rack, secured to the storage frame, so that rotation of the torque tube by a horizontal drive motor causes concurrent horizontal drive movement along the toothed rack. When the horizontal drive motor is braked to a halt, rotation of the torque tube is terminated, thereby preventing sway in the upper vertical mast.

The torque tube which extends along the entire length of a tall vertical mast is both cumbersome and expensive. While the torque tube provides horizontal drive opposite the motor driven end of the stacker crane, powered drive at solely one end of the stacker crane is' sufficient to accurately control horizontal movement along a storage framework.

In accordance with the present invention, the 'necessity for torque tubes and the like on tall stacker cranes is eliminated. An alignment brake is located at the undriven end of a tall mast. When the driven end is braked to a halt, a master cylinder hydraulically clamps a pair of normally disengaged caliper elements against a smoothelongated brake guide. In one embodiment best suited 'for some cranes, the caliper elements are disengaged after a short time delay, allowing any vertical offset to be corrected at the same time that load forks are extending into a storage bin.

Also in accordance with the present invention, an improved brake mechanism for a stacker crane consists of caliper elements which grip opposed sides of a horizontal guide rail. The resulting braking action is an improvement over conventional stacker crane braking action which electrically or mechanically slows the movement of a wheel driven along a horizontal guide rail.

Further features and advantages of the invention will be apparent from the following description, and from the drawings, 'in which:

FIG. 1 is a side elevational view looking down a storage aisle of a warehousing system embodying the invention; I

FIG. 2 is a front elevational view of the stacker crane shown in FIG. 1;

FIG. 3 is a front plan view of a caliper brake mechanism mounted at the top of the stacker crane shown in FIGS. 1 and 2; I

FIG. 4 is a side plan view taken along lines 4-4 of FIG. 3, with certain elements being brokenaway for clarity; and I 3 FIG. 5 is a block diagram of a control for opera ing the stacker crane and caliper brake mechaniszix'.

While an illustrative embodiment of the invention is shown in the drawings and will be described in detail herein, the invention is susceptible of embodiment in many different forms and it should be understood that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated.

In FIGS. 1 and 2,.a warehousing system is illustrated using a tall stacker crane 20 of a type suitable for use with the invention. The stacker crane 20 is driven along a narrow aisle of an elongated storage framework consisting of left and right rows of horizontally extending and vertically stacked storage bins 22. The illustrated stacker crane is a floor-driven unit propelled along an I-beam guide rail 24 which extends horizontally down the middle of the aisle. A smooth guide tube or rail 26, which also serves as an alignment brake surface, extends near the ceiling or roof of the warehouse, and is mounted off-center of the aisle by a cross-tie beam 28 which is attached to vertical beams 30 extending above the top of the uppermost storage bins 22.

.A horizontal crane carriage 32 is guided along horizontal railgibya drive wheel 34 and an idle wheel 34a which ride on the upper surface of the rail 24. A horizontal drive motor 35, which includes an internal electrically or mechanically enabled brake, is coupled through a speed slow-down brake 37 to a helical worm speed reducer 39 which rotates drive wheel 34 in order to propel the carriage 32 horizontally along the storage aisle.

A tall vertical mast structure extends upward from the horizontal carriage 32, and includes a pair of spaced columns 40 and 42 which are rigidly tied together through an upper carriage frame 46 which mounts a hoist mechanism and a novel alignment mechanism, to be explained. The frame 46 rotatably mounts a hoist shaft 48 driven through a helical worm reducer 50 by a hoist motor and brake apparatus 52. A pair of chain belts 56 and 58, wound on hoist shaft 48, connect to a vertical hoist carriage 60 which is vertically propelled between the spaced columns by energization of motor 52. Mounted on vertical hoist carriage 60 is a conventional fork mechanism 62 which can be horizontally propelled, to either the right or left as illustrated in FIG. l, in order to deposit or retrieve a pallet 64 holding material 65 in one of the storage bins 22.

The stacker crane 20 may be operated automatically under control of externally generated signals, or manually by an operator standing in an operators cab and actuating control switches on an operator panel 72. Many other conventional structural and control elements, not illustrated for clarity, may be provided as desired.

To vertically capture and center the stacker crane 20 within the storage aisle, guide rollers 76 freely rotate on pins extending from carriage 32 abut each side of the lower rail 24. Similar guide rollers 78, freely rotatable on pins extending from the upper carriage frame 46, abut both vertical sides of the upper guide rail 26.

In accordance with the present invention, a caliper brake mechanism 1 0 is attached to the upper carriage frame 46 to brake movement of the upper columns 40, 42 when the brake in horizontal motor 35 is enabled to stop movement of the crane. When columns 40 and 42 extend fifty or more feet, the upper carriage frame 46 will sway or swing by one inch or more when the horizontal motor brake is enabled. This amount of sway is too great to safely allow the fork mechanism 62 to be propelled intoan upper storage bin 22. This problem is overcome by simultaneously actuating alignment brake mechanism 90 and the horizontal motor brake 35, allowing the fork mechanism 62 to be immediately extended as soon as it is adjacent a selected bin.

Due to the great height and inertia of the columns 40, 42 and the different construction of the two brakes, it is possible for the upper carriage 46 to be vertically offset from the bottom carriage 32 by a small distance, such as 0.3 inches, when the crane comes to a halt. This offset is not great enough to create a safety problem with respect to extending the fork mechanism 62. However, to insure exact positioning of the fork by the time it is fully extended, brake mechanism 90 is released after a short time delay, allowing frame 46 to come back a distance of 0.3 inches or so which thus causes no significant vertical misalignment throughout the entire length of the vertical hoist structure. The tendency for the vertical mast to sway, when released by brake mechanism 90, is quickly damped out due to the small degree of offset, and because the stacker crane is at rest when the brake mechanism 90 is released. This improved brake action allows elimination of torque tubes and other mechanisms for preventing sway in the vertical mast structure.

Brake mechanism 9.0 is illustrated in detail in FIGS. 3 and 4. A base plate 100, riveted to carriage frame 46, mounts the electrical and hydraulic mechanism for controlling a pair of caliper brake elements 102 and 103 which are attached by posts 105 to a'support plate 106 also riveted to the vertical frame 46. An electrically energizable solenoid 110 is fixed to an L-beam 1 12 attached to base plate 100. The mounting structure aligns the solenoid core or movable armature 114 vertically with respect to ground, for reasons to be explained. The solenoid armature 114 includes a head 116 having a pair of flat shoulders 118 which rest against the upper surface housing 120 of solenoid 110 when the solenoid is energized and draws the armature 114 downward. Armature head 116 is coupled through a bell crank assembly 130 with a master cylinder 132 which forces hydraulic brake fluid through a pair of output hoses 134 and 136 when a cylinder push rod 140 is urged into the master cylinder.

Bell crank assembly 130 is pivoted about a pivot post 150 which is fixed to base plate 100. A connecting pin 152 couples a vertically extending arm of hell crank 130 to push rod 140. A connecting pin 154 couples a horizontally extending arm of bell crank 130 to a consurface 120 of solenoid l due to solenoid action, and

also due to the action of gravity which aids the solenoid action. The vertical alignment of the solenoid armature eliminates the seating problems which otherwise tend 1 necting link 156 which is coupled to armature head 118 to occur when a solenoid is energized for long periods of time.

To move the bell crank assembly clockwise when solenoid 110 is deenergized, a compression spring is captured between a spring mounting plate 172, secured to base plate 100, a spring retaining ring washer 174 held by hex jam nuts 175 threaded on a rod 177. One end of rod 177 is coupled through a connecting pin 180 with the vertically extending arm of the crank assembly 130, while the other end is slidably received within an aperture in plate 172. As solenoid 110 is deenergized, compression spring 170 rotates crank assembly 130 clockwise, urging push rod 140 into the hydraulic master cylinder 132.

As seen in FIG. 4, each caliper element 102 and 103 contains a piston having a brake lining 192 closely spaced from the smoothvertical side walls of the guide tube 26. When master cylinder 132 is actuated, hydraulic brake fluid flows through hoses 134 and 136 into a closed space behind each piston 190, exerting equal pressures on the brake linings. The brake action is selfadjusting, since each caliper brake element receives the amount of hydraulic brake fluid necessary to equally engage the opposed facing brake surfaces of guide 26. When solenoid 110 is again actuated, solenoid armature 114 is magnetically pulled into the solenoid, rotating bell crank 130 counterclockwise to relieve the pressure on the master cylinder 132, thereby disengaging the pair of caliper brakes.

Any crane control can be used which is capable of energizing solenoid 110 at the same time that the horizontal motor is braked to a halt. By way of example, a control suitable for use with the invention is illustrated in FIG. 5. The control is of the type disclosed in detail by applicant James S. l-lathcock, Jr. in patent application Ser. No. 8l0,494, filed Mar. 26, l969, and assigned to the assignee of the present application. As disclosed in said application, to which reference should be made for a detailed description, external command information transmitted to an information input 200 is coupled to a command address memory 202 which records unique binary numbers which identify both the horizontal and vertical positions of a desired bin. The stored address or number is coupled to a horizontal control unit 204, and to a generally similar vertical control unit 206.

Horizontal control unit 204 includes a subtractor 210 which subtracts the stored command address C from an actual position address P available from a horizontal position unit 212. Unit 212 may be coupled to a horizontal indicia sensor 214 mounted in a conventional manner on the horizontal carriage 32, FIG. 2, in order to scan unique indicia associated with the horizontal rail 24. A similar vertical indicia sensor 216 may be mounted on the vertical carriage 60 in order to scan vertical addresses attached to one of the columns 40 or 42.

Subtractor 210 is effective to subtract the command address C from the actual position address P and produce outputs which are coupled to a difference detector 220 and to an overflow detector 222. Direction of travel information is determined by overflow detector 222 which senses whether subtractor unit 210 has an overflow borrow condition. That is, if the subtracted difference (C-P) is positive, the borrow computations do not overflow, indicating that the commanded address is in advance of the present position, and therefore the stacker crane should 'move in a direction, arbitrarily designated forward, to decrease the difference. Conversely, if the subtracted difference (C-P) has a negative number, indicated by an overflow borrow condition, the stacker crane should move in the opposite direction, arbitrarily designated reverse.

- The overflow detector 222 is gated or rendered effective each time a fine position sensor 226 detects a suitable trigger indicia which indicates that the data from the horizontal indicia sensor 214 is valid at that time. Such detection gates the signal from overflow detector 222 to a direction control 230. The resulting forward or reverse direction-of-travel signal is coupled to a known horizontal motor control 234 for directional control of the horizontal motor.

To control the speed of travel of the stacker crane, including slowdown and stopping at a selected bin, the difference detector 220 determines the absolute value of the difference number (C-P) from the subtractor unit 210. When one of a plurality of preselected absolute value differences D is recognized, a corresponding output 240 is generated. In the present example, outputs 240 are illustratively provided when the stacker crane is located N, l and 0 bins away in either direction from the selected bin, namely when D=N, D=l, and D=0, respectively. I All of the outputs 240 are coupled to horizontal motor control 234 to control the speed of the motor. When D=N and D==l, the horizontal motor control 234 actuates the separate horizontal slowdown brake 37, such as an eddy current brake, to slow the crane speed in anticipation of reaching a selected bin. A speed control output 250 from horizontal motor control 234 may also slow the hrizontal motor 35, as by cutting back the firing angles of SCRs which supply power to the motor, or by other conventional techniques.

When a difference of zero is detected, the D=0 output 240 generates a signal which inputs to horizontal motor control 234 and to an AND gate 254. The horizontal motor control 234 now terminates electrical drive for the horizontal motor, and actuates the internal horizontal motor brake, which may operate on electrical or mechanical principles, in order to stop all horizontal motion. r

The vertical control 206 operates in generally the same manner as the horizontal control 204, controlling the speed of the'vertical motor and brake 52. When the vertical indicia sensor 216 senses the vertical address storedin memory 202, vertical control 206 terminates actuation of the motor 52, sets the internal electrical or mechanical brake therein, and also outputs a D=O signal which inputs to AND gate 254. Since both inputs of AND gate 254. are now present, an output actuates a fork control 260, energizing a fork motor 262 which drives the fork mechanism 62 of FIG. 2. The fork mechanism now enters a storage bin and deposits or retrieves a load, as programmed by other conventional control apparatus, not illustrated. Desirably, the vertical control 206, the fork control 260, and the horizontal motor control 234 all have manual inputs which allow an operator to manually control the stacker crane. For some installations, only manual control may be desired.

To control the novel caliper brake mechanism, line 250 is coupled to a brake control 270 which maintains solenoid energized whenever any speed control signal is present from horizontal motor control 234. If

the caliper brake is to remain energized during the entire time that the stacker crane is horizontally at rest,

brake control 270 can take the form of a relay having contacts which couple power across solenoid 110 at all times when the brake in horizontal motorj35 is not enabled. Upon termination of the drive signal on line 250,

the relay would be deenergized, open circuiting solenoid 110 to enable the caliper brake.

Preferably, the caliper brake is disabled after the lapse of a short time period, such as one second, after actuation of the horizontal motor brake. As previously explained, disabling of the caliper brake corrects and quickly damps any vertical offset. For this. purpose, fork control 260 has an output line 280 which causes brake control 270 to re-enable energization of solenoid 110 upon the lapse of a short time period after appearance of the fork signal on line 280. Thus, brake control 270 actuates the caliper brake immediately when a horizontal carriage is braked. If the vertical carriage is not yet-braked, the caliper brake remains energized. When the vertical carriage comes to a halt, the forks extend and, after the lapse ofone second, the caliper brake is deenergized.

The caliper brake mechanism can be used generally for stopping movement of a stacker crane, separate from its use as an alignment brake/The crane control can be replaced with other crane controls which'can be modified to actuate the caliper brake solenoid 110 simultaneously with actuation of a horizontal electrical or mechanical brake. Other modifications will be apparent to those skilled in the art.

I claim: 4

l. A warehousing system comprising:

a storage framework with a plurality of load containing storage bins spaced horizontally along the length of a warehouse and stacked vertically on top of each other;

. elongated horizontal guide means extending substantially parallel to the horizontally spaced storage bins;

self-propelled conveyor means including a carriage with drive and brake means thereon for driving and stopping said carriage along said horizontal guide means;

elongated column means mounted on said carriage and extending vertically therefrom a sufficient distance to undesirably allow vertical misalignment and sway between the carriage and a vertically opposed section of said column means when the speed of movement of the carriage is changed by said drive and brake means; a r r hoist means mounted for movement along said column means to propel a load vertically and to deposit and retrieve a load from a storage bin;

elongated brake surface means extending substantially parallel to and spaced from the elongated horizontal guide means and located adjacent the opposed section of said column means;

alignment brake means mounted on the opposed section of said column means and actuable to urge a disengaged brake element against said elongated brake surface means to stop movement of the oppos'ed section of said column means, including electrically actuated means for moving a member, mechanically actuated means responsive to the position of said member for urging said disengaged brake element against said elongated brake surface means including master cylinder means responsive to movement of a push rod for urging hydraulic fluid through tubing means, link means for coupling said push rod to said member, said brake element includes housing means having piston means movable therein, said tubing means being coupled to said housing means to urge said piston means towards said elongated brake surface means in response to pressure of said hydraulic fluid; and control means for electrically controlling said electrically actuated means when said drive and brake means stops said carriage to cause brake element to engage said elongated brake surface means and thereby prevent vertical sway of the column means,

2. The warehousing system of claim 1 wherein said electrically actuated means comprises a solenoid having an armature movable from a first to a second position in response to energization of said solenoid, and mounting means attaching said solenoid to said opposed section of said column means with a vertical alignment of said armature to cause gravity to aid vertical movement thereof to said second position.

3. The warehousing system of claim 1 wherein said housing means includes a pair of housing sections located on opposed sides of said elongated brake surface means, said piston means comprises a pair of piston elements mounted within said pair of housing sections and driven by said hydraulic fluid in opposed directions against said opposed sides to produce caliper brake action.

4. The warehousing system of claim 1 wherein said control means includes brake off means for deactuating said alignment brake means after the lapse of a time period occuring after said drive and brake means stops said carriage, allowing correction for any vertical offset in said column means.

5. The warehousing system'of claim 4 wherein said hoist means includes fork means for moving horizontally into and out of a storage bin under control of a fork motor, and said control means includes fork control means for energizing said fork motor after said drive and brake means has stopped said carriage.

6. The warehousing system of claim 1 including column guide means attached to said vertically opposed section for holding said elongated column means against said elongated brake surface means, whereby said elongated brake surface means serves as an alignment brake surface and as a vertical support for said self-propelled converyor means.

7. The warehousing system of claim 6 wherein said elongated brake surface means has a pair of vertically extending sides and a horizontally extending cross member between said vertically extending sides, frame means fixedly attaching said cross member to said storage framework, said column guide means comprises a pair of opposed guide surfaces abutting said vertically extending sides of said elongated brake surface means, and said alignment brake means is actuable to urge'said disengage brake element against at least one of said vertically extending sides.

8. The warehousing system of claim 7 wherein said brake element comprises a caliper brake having a pair of movable members with brake lining means affixed to the end of each movable member, means mounting said movable members on opposed sides of said vertically extending sides, and pressure means for urging with substantially equal pressures the movable members towards said vertically extending sides. 

1. A warehousing system comprising: a storage framework with a plurality of load containing storage bins spaced horizontally along the length of a warehouse and stacked vertically on top of each other; elongated horizontal guide means extending substantially parallel to the horizontally spaced storage bins; self-propelled conveyor means including a carriage with drive and brake means thereon for driving and stopping said carriage along said horizontal guide means; elongated column means mounted on said carriage and extending vertically therefrom a sufficient distance to undesirably allow vertical misalignment and sway between the carriage and a vertically opposed section of said column means when the speed of movement of the carriage is changed by said drive and brake means; hoist means mounted for movement along said column means to propel a load vertically and to deposit and retrieve a load from a storage bin; elongated brake surface means extending substantially parallel to and spaced from the elongated horizontal guide means and located adjacent the opposed section of said column means; alignment brake means mounted on the opposed section of said column means and actuable to urge a disengaged brake element against said elongated brake surface means to stop movement of the opposed section of said column means, including electrically actuated means for moving a member, mechanically actuated means responsive to the position of said member for urging said disengaged brake element against said elongated brake surface means including master cylinder means responsive to movement of a push rod for urging hydraulic fluid through tubing means, link means for coupling said push rod to said member, said brake element includes housing means having piston means movable therein, said tubing means being coupled to said housing means to urge said piston means towards said elongated brake surface means in response to pressure of said hydraulic fluid; and control means for electrically controlling said electrically actuated means when said drive and brake means stops said carriage to cause brake element to engage said elongated brake surface means and thereby prevent vertical sway of the column means.
 2. The warehousing system of claim 1 wherein said electrically actuated means comprises a solenoid having an armature movable from a first to a second position in response to energization of said solenoid, and mounting means attaching said solenoid to said opposed section of said column means with a vertical alignment of said armature to cause gravity to aid vertical movement thereof to said second position.
 3. The warehousing system of claim 1 wherein said housing means includes a pair of housing sections located on opposed sides of said elongated brake surface means, said piston means comprises a pair of piston elements mounted within said pair of housing sections and driven by said hydraulic fluid in opposed directions against said opposed sides to produce caliper brake action.
 4. The warehousing system of claim 1 wherein said control means includes brake off means for deactuating said alignment brake means after the lapse of a time period occuring after said drive and brake means stops said carriage, allowing correction for any vertical offset in said column means.
 5. The warehousing system of claim 4 wherein said hoist means includes fork means for moving horizontally into and out of a storage bin under control of a fork motor, and said control means includes fork control means for energizing said fork motor after said drive and brake means has Stopped said carriage.
 6. The warehousing system of claim 1 including column guide means attached to said vertically opposed section for holding said elongated column means against said elongated brake surface means, whereby said elongated brake surface means serves as an alignment brake surface and as a vertical support for said self-propelled converyor means.
 7. The warehousing system of claim 6 wherein said elongated brake surface means has a pair of vertically extending sides and a horizontally extending cross member between said vertically extending sides, frame means fixedly attaching said cross member to said storage framework, said column guide means comprises a pair of opposed guide surfaces abutting said vertically extending sides of said elongated brake surface means, and said alignment brake means is actuable to urge said disengage brake element against at least one of said vertically extending sides.
 8. The warehousing system of claim 7 wherein said brake element comprises a caliper brake having a pair of movable members with brake lining means affixed to the end of each movable member, means mounting said movable members on opposed sides of said vertically extending sides, and pressure means for urging with substantially equal pressures the movable members towards said vertically extending sides. 